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September 21, 2009

Ozone depletion might be getting better

by Sam Savage

Scientists using European Space Agency satellite data say they've discovered the depletion of the Earth's ozone layer might be easing.

We found a global slightly positive trend of ozone increase of almost 1 percent per decade in the total ozone from the last 14 years: a result that was confirmed by comparisons with ground-based measurements, said Diego Loyola, who worked on the project with colleagues from the German Aerospace Center.

Ashley Jones and Jo Urban from Sweden's Chalmers University of Technology and colleagues analyzed the long-term evolution of stratospheric ozone from 1979 to the present. These data show a decrease in ozone from 1979 until 1997, and a small increase since then, the ESA said.

Our analysis shows that upper stratospheric ozone declines at northern and southern mid-latitudes at roughly 7 percent per decade during 1979"“97, consistent with earlier studies based on data from satellites and ground networks, Urban said. A clear statistically significant change of trend can be seen around 1997. The small increase observed thereafter, from 1997 to 2008, is however not yet statistically different from a zero trend. We hope to see a significant recovery of (upper stratospheric) ozone in the next years using longer, extended satellite time-series.

The study was presented earlier this month in Barcelona, Spain, during the ESA's Atmospheric Science Conference.